5. Comparing Annual Heating Costs

5. Comparing Annual Heating Costs

The combination of heating load, energy source and equipment efficiency determines the annual cost of heating.

Heating Costs When Upgrading Your Existing Gas Heating System

If you are heating with gas and are thinking of converting to a more efficient gas heating system, you may be interested in calculating the savings you could expect. Using Table 1 (on page 49) and the following formula will provide you with reasonably accurate figures. You need to know your annual fuel cost and the type of heating technology you are using. (Note: the published AFUE for propane-fired appliances is based on firing with natural gas. This rating should be adjusted in accordance with the footnotes to Table 1 to arrive at a more accurate rating for calculation purposes.)

Equation 1

Annual $ savings =

A – B-----------A

x C

Where

A = Seasonal efficiency of the proposed system

B = Seasonal efficiency of the existing system

C = Present annual fuel cost for space heating

Example: How much would you save by changing from a conventional gas furnace to a high-efficiency gas furnace at 96 percent efficiency if your present annual gas cost for space heating is $800?

The seasonal efficiency of the new condensing furnace is 96 percent,and the efficiency of your present gas furnace is 60 percent.Hence, A =96 percent, B =60 percent and C =$800.

Annual $ savings =

96– 60-----------96

= $300

x 800

Thus, you would save $300 a year in energy costs by installing a high-efficiency gas furnace, and you would also eliminate the need for a chimney.

Table 1

Gas Heating Appliances –Features andEfficiency Ranges

Type

Features

SeasonalEfficiency(AFUE) (%)

Conventional furnace1

chimney

draft hood

with continuously lit pilot light

with electronic ignition and vent damper

6062–67

Conventional boiler1

chimney

draft hood

with continuously lit pilot light

with electronic ignition and vent damper

55–6560–70

Standard-efficiency furnace1

chimney or side wall vent

draft hood

electric ignition

powered exhaust

78–84

Standard-efficiency boiler1

similar to mid-efficiency furnace

80–88

Condensing furnace2

no chimney

no draft hood

electric ignition

multi-stage heat exchanger

condenses water vapour from flue gases

PVC or ABS flue pipe to side wall

90–97

Condensing boiler 2,3

similar to condensing furnace

89–993

Conversion burners for oil equipment1

chimney

pilot light or electric ignition

special barometric damper or draft hood

63–68

Direct-vent wall furnace1

vent

sealed combustion

pilot light or electric ignition

70–82

Room heaters1

vent

pilot light or electric ignition

draft hood or sealed combustion

60–82

1 If this appliance is fired with propane rather than natural gas, add 2 percent to the efficiency.2 If a condensing appliance is fired with propane rather than natural gas, subtract 2 percent from the efficiency.3See pages 37–38 for conditions affecting condensing boiler efficiency.

HEATING COSTS WITH DIFFERENT ENERGY SOURCES

You may be interested in calculating the cost of heating with gas compared with the cost of heating with other energy sources, such as electricity, propane, oil or wood. If this is the case, you can use the following procedure (Steps 1 to 4). You need to find out the cost of the energy sources you want to compare and the types of heating technologies you might want to use.

Step 1. Determine the Price of Energy Sources in Your Area

Call your local fuel and electricity suppliers to find out the cost of energy sources in your area. This should be the total cost delivered to your home, and it should include any basic cost that some suppliers might charge, along with necessary rentals, such as a propane tank. Be sure to get the prices for the energy sources in the same units as shown in Table 2. Write the costs in the spaces provided. If your local natural gas price is given in gigajoules (GJ), you can convert it to cubic metres (m3) by multiplying the price per gigajoule by 0.0375. For example,

Step 2. Select the Type of Heating Appliance

Choose the type of equipment you want to compare from the list of appliance types in Table 3 on page 52. Note the efficiency figures in the column titled "Seasonal Efficiency." By using these figures, you can calculate the savings you can achieve by upgrading an older system to a newer, more energy-efficient one or by choosing a higher-efficiency appliance that uses an alternative energy source.

Step 3. Determine Your Home's Annual Heating Load

If you know your bill for space heating and the unit cost of your energy source, you can determine your annual heating load in gigajoules from the following equation:

Equation 2

Annual Heating Load

=

Heating Bill-----------------100 000

x

Seasonal Efficiency-----------------------------Energy Cost/Unit

x

EnergyContent

For example,you have been able to determine that your annual bill for space heating with natural gas is $687, gas costs $0.22/m3, and you have an old conventional gas furnace with a seasonal efficiency of 60 percent (see Table 3).

The energy content of natural gas is 37.5 MJ/m3 (see Table 2).

Annual Heating Load

=

687-----------------100 000

x

60---------0.22

x

37.5 = 70 GJ

If your bills also include tap water heating and even equipment rentals, you can still calculate your annual heating load, but it will require a little more care and calculation to separate your heating-only portion.

If you cannot get your heating bills, you can estimate your annual heating load in gigajoules from Table 4 on page 53 by selecting the house type and location that is closest to you.

Table 3

Typical Heating System Efficiencies and Energy Savings

EnergySource

Technology

SeasonalEfficiency(AFUE) %

EnergySavings% of Base1

NaturalGas

Conventional furnace/boiler

60

Base

Standard-efficiency furnace

78–84

23–28

Standard-efficiency boiler

80–88

25–32

Condensing furnace

90–97

33–38

Condensing boiler

89–99

33–39

Integrated space/ tap water condensing

90–96

33–38 space44–48 water

Propane

Conventional furnace/boiler

62

Base

Standard-efficiency furnace

79–85

21–27

Standard-efficiency boiler

82–90

24–31

Condensing furnace

88–95

29–34

Condensing boiler

87–97

29–36

Oil

Cast-iron head burner (old furnace)

60

Base

Flame-retention head replacement burner

70–78

14–23

High-static replacement burner

74–82

19–27

New standard model

78–86

23–30

Standard-efficiency

83–89

28–33

Integrated space/tap water standard-efficiency

83–89

28–33 space40–44 water

Electricity

Electric baseboards

100

N/A

Electric furnace or boiler

100

Air-source heat pump

1.7 COP2

Earth-energy system(ground-source heat pump)

2.6 COP2

Wood

Central furnace

45–55

N/A

Conventional stove (properly located)

55–70

"High-tech" stove3 (properly located)

70–80

Advanced combustion fireplace

50–70

Pellet stove

55–80

1Base represents the energy consumed by a conventional furnace.2COP = Coefficient of Performance, a measure of the heat delivered by a heat pump over the heating season per unit of electricity consumed.3CSA B415 or EPA Phase II tested.

Table 4

Typical Annual Heating Loads in Gigajoules (GJ) for Various Housing Types in Canadian Cities

City

Old Detached

New Detached

New Semi-Detached

Town-house

Victoria

85

60

45

30

Prince George

150

110

80

60

Calgary

120

90

65

50

Edmonton

130

95

70

55

Fort McMurray/Prince Albert

140

105

80

60

Regina/Saskatoon/Winnipeg

130

90

70

50

Whitehorse

155

115

85

60

Yellowknife

195

145

110

80

Thunder Bay

130

95

70

55

Sudbury

120

90

65

50

Ottawa

110

75

55

40

Toronto

95

65

45

35

Windsor

80

55

40

30

Montréal

110

80

60

45

Québec

115

85

65

50

Chicoutimi

125

90

70

55

Saint John

105

75

60

45

Edmundston

120

90

65

50

Charlottetown

110

80

60

45

Halifax

100

75

55

40

St. John's

120

85

60

45

Note: "New "means houses built in 1990 or later, and "old "means houses built before 1990. Due to construction practices, "weatherizing " and re-insulating (which can be different from house to house) , these figures are meant to be used only as general guidelines; they should not substitute for an accurate heating requirement determination, as discussed in Chapter 5.

Equation 3

Enter the cost per unit of energy and divide it by the energy content of the energy source – both numbers come from Table 2 on page 50.

Select the heating load for your type of housing and location from Table 4 on page 53, and divide it by the seasonal efficiency of the proposed heating system from Table 3 on page 52.

Multiply the results of these two calculations, then multiply that result by 100 000.

The result should give you an approximate heating cost for your house. If you know your actual heating costs and the type of heating system you have, you can modify the heating load originally taken from Table 4 to suit your specific house.

Sample Calculation: You have an old detached home in Edmundston, and you would like to find out what the annual heating cost would be with a high-efficiency condensing natural gas furnace at 96 percent efficiency with gas costing $0.18/m3. The house heating load is 120 GJ (see Table 4), and the energy content is 37.5 MJ/m3 (see Table 3).

$0.18-------------------37.5

x

120----------------96

x 100 000 = $600

If you would like to compare this heating cost with that of other types of heating systems or energy sources, replace the numbers in the formula with the appropriate ones for your comparison using Tables 2 and 3.